短程硝化-反硝化生物脱氮技术研究

将短程硝化-反硝化生物脱氮技术与传统生物脱氮技术进行了比较,论述了短程硝化-反硝化生物脱氮技术的机理及特点。分析了实现亚硝酸盐积累的影响因素,包括温度、溶解氧浓度、pH值、分子态游离NH3浓度和泥龄。结合典型工艺,提出了目前短程硝化-反硝化脱氮技术存在的问题及改进建议。     

短程硝化反硝化生物脱氮的实现途径

短程硝化反硝化是近年来开发的一项新的生物脱氮技术,它具有节约曝气量、节省有机碳源和减少污泥产量等优点,实现短程硝化反硝化生物脱氮技术的关键就是将硝化控制在亚硝酸阶段,阻止亚硝酸盐的进一步氧化。简要介绍了短程硝化反硝化生物脱氮技术的原理和技术特点,通过对短程硝化反硝化影响因素的分析来介绍其实现途径,阐述了温度控制途径、溶解氧控制途径、pH值控制途径、投加抑制剂途径、泥龄控制途径以及纯种分离与固定化技术途径的控制机理及其局限性,并提出了今后的研究方向。     

短程硝化--反硝化生物脱氮工艺的研究进展

短程硝化反硝化生物脱氮工艺是将硝化控制在形成亚硝酸阶段,阻止亚硝酸的进一步硝化,然后直接进行反硝化。本文结合国内外的研究,对短程硝化脱氮技术的实现途径进行了概括和探讨,对该工艺的开发应用（如SHARON工艺、OLAND工艺、CANONT艺和生物膜／活性污泥法结合的短程硝化反硝化工艺）作了简要综述,并指出了该工艺的技术优势和应用价值。     

两段SBR工艺脱氮规律实验研究

基于对生物硝化反硝化原理的分析,本实验选用两段SBR工艺生物脱氮技术,解决了高浓度工业废水有机物去除效率高而氨氮去除率不高的难题。同时对其脱氮规律作了研究,找到SBR2是脱氮的关键环节,并分别对SBR2硝化反硝化阶段p H和DO的变化规律进行了研究,得出用这两个参数作为系统自动控制的依据是完全可行的。     

废水生物脱氮低温反硝化研究进展

反硝化过程是废水生物脱氮的关键,低温下废水生物处理的反硝化效率显著降低.本文从低温对微生物反硝化处理效果的影响、低温对反硝化微生物的影响机制以及低温下反硝化效果的强化策略等方面的研究展开综述,并提出了可能的研究方向,以期为微生物低温反硝化进一步的机理研究与技术强化提供参考.     

一种适用于低碳(超低碳)高浓度含氮废水生物脱氮工艺的探讨

传统的生物脱氮工艺对于低（超低）COD／NH4^ 条件下废水的脱氮效果很差，甚至没有脱氮效果，因为传统的生物脱氮工艺在反硝化过程中需要大量的电子供体。亚硝酸型硝化和厌氧氨氧化有机结合构成新型的生物脱氮工艺，为低碳（超低碳）高浓度含氮废水提供他一种崭新的生物脱氮工艺。但其间的反应机理，控制条件等都需进一步的研究和探讨。     

焦化废水生物脱氮工艺的探讨

焦化废水是一种氨氮和有机物浓度较高的难生化降解有机废水。随着排放指标的日益严格,出现了很多焦化废水的处理新技术,而焦化废水的生物脱氮技术的发展是其中非常重要的一个方面。本文以生物脱氮硝化／反硝化反应的反应途径为线索,系统分析了国内外近年来在焦化废水生物脱氮方面的研究进展,并简要介绍了国外一些生物脱氮的新技术,包括SHARON工艺、OLAND工艺和ANAMMOX工艺。     

氨氮废水处理技术的发展

氨氮去除方法有多种,物理化学法有空气吹脱法、折点氯化法、化学沉淀法、液膜法、电渗析除氨氮法、催化湿式氧化法、土壤灌溉法、循环冷却水系统脱氨法;生物脱氮法可去除多种含氮化合物,总氮去除率可达70%-95%,主要有传统硝化反硝化、短程硝化反硝化、同时硝化反硝化、厌氧氨氧化.有时要采取多种技术的联合处理,才能取长补短达到较好的处理效果.     

废水生物脱氮除磷机理与技术研究的进展

本文介绍了硝化－反硝化，短程硝化－反硝化，厌氧氨氧化等生物脱氮 过程和生物除磷过程的机理及目前国内外的研究现状和比较成熟的技术，并对我国开展这方面的研究前景提出了展望。     

SBR系统反硝化除磷研究进展

本文结合近年来国内外最新研究成果，对SBR系统反硝化除磷的机理、过程进行了分析、总结。并重点探讨了NO2^-对反硝化除磷的影响，以期为传统脱氮除磷工艺的研究、改进提供新思路。     

Limited occurrence of denitrification in four shallow aquifers in agricultural areas of the United States

The ability of natural attenuation to mitigate agricultural nitrate contamination in recharging aquifers was investigated in four important agricultural settings in the United States. The study used laboratory analyses, field measurements, and flow and transport modeling for monitoring well transects (0.5 to 2.5 km in length) in the San Joaquin watershed, California, the Elkhorn watershed, Nebraska, the Yakima watershed, Washington, and the Chester watershed, Maryland. Ground water analyses included major ion chemistry, dissolved gases, nitrogen and oxygen stable isotopes, and estimates of recharge date. Sediment analyses included potential electron donors and stable nitrogen and carbon isotopes. Within each site and among aquifer-based medians, dissolved oxygen decreases with ground water age, and excess N(2) from denitrification increases with age. Stable isotopes and excess N(2) imply minimal denitrifying activity at the Maryland and Washington sites, partial denitrification at the California site, and total denitrification across portions of the Nebraska site. At all sites, recharging electron donor concentrations are not sufficient to account for the losses of dissolved oxygen and nitrate, implying that relict, solid phase electron donors drive redox reactions. Zero-order rates of denitrification range from 0 to 0.14 micromol N L(-1)d(-1), comparable to observations of other studies using the same methods. Many values reported in the literature are, however, orders of magnitude higher, which is attributed to a combination of method limitations and bias for selection of sites with rapid denitrification. In the shallow aquifers below these agricultural fields, denitrification is limited in extent and will require residence times of decades or longer to mitigate modern nitrate contamination.     

人工湿地污水处理系统脱氮机理研究进展

本文介绍了近年来人工湿地污水处理系统脱氮机理的研究情况,阐述了人工湿地脱氮的三种途径：植物和其它生物的吸收作用、微生物的生物转化作用及氨气的挥发作用,其中微生物的生物转化作用是人工湿地主要的脱氮方式.同时对影响人工湿地脱氮效率的主要因素：温度、pH值、氧化还原电位、溶解氧、微生物可利用有机碳与硝态氮、停留时间等都作了比较详细的介绍,为进一步开展人工湿地脱氮机理的研究和优化人工湿地污水处理系统设计提供参考.     

A methodology to estimate the denitrifying capacity of a riparian wetland

Numerous studies have shown that riparian wetlands can play an important role in reducing nitrate concentrations before the ground water discharges into streams. Denitrification has been identified as an important process for this removal. Several approaches have been proposed to predict the denitrifying removal capacity of a riparian wetland, but no widely used tool exists to precisely quantify this capacity at the landscape scale. We propose such a methodology based on modeling the spatial variation of soil-water interactions in the entire riparian wetland. Mean values of denitrification enzyme activity (DEA) within three soil-denitrifying classes were 604, 212, and 24 ng N g(-1) h(-1) for Classes 3, 2, and 1, respectively. The study area, having a ground surface of about 15000 m2, was underlain by an aquifer with a calculated volume of 60000 m3, less than 10000 m3 of which corresponded to active denitrifying horizons (Classes 2 and 3). By volume, approximately 30% of Class 3 and 70% of Class 2 were interacting with ground water. The denitrifying removal capacity of our wetland was calculated to be about 1.8 kg N m(-2) yr(-1). The calculated denitrifying capacity of our site was less than expected. This is due to the fact that not all ground water interacts with the horizons having the highest denitrifying capacity. Thus, we show that whatever the system is, specific local pedological and hydrogeological conditions and their interactions are paramount in controlling the denitrification process.     

Potential nitrification and denitrification on different surfaces in a constructed treatment wetland

Improved understanding of the importance of different surfaces in supporting attached nitrifying and denitrifying bacteria is essential if we are to optimize the N removal capacity of treatment wetlands. The aim of this study was therefore to examine the nitrifying and denitrifying capacity of different surfaces in a constructed treatment wetland and to assess the relative importance of these surfaces for overall N removal in the wetland. Intact sediment cores, old pine and spruce twigs, shoots of Eurasian watermilfoil (Myriophyllum spicatum L.), and filamentous macro-algae were collected in July and November 1999 in two basins of the wetland system. One of the basins had been constructed on land that contained lots of wood debris, particularly twigs of coniferous trees. Potential nitrification was measured using the isotope-dilution technique, and potential denitrification was determined using the acetylene-inhibition technique in laboratory microcosm incubations. Nitrification rates were highest on the twigs. These rates were three and 100 times higher than in the sediment and on Eurasian watermilfoil, respectively. Potential denitrification rates were highest in the sediment. These rates were three times higher than on the twigs and 40 times higher than on Eurasian watermilfoil. The distribution of denitrifying bacteria was most likely due to the availability of organic material, with higher denitrification rates in the sediment than on surfaces in the water column. Our results indicate that denitrification, and particularly nitrification, in treatment wetlands could be significantly increased by addition of surfaces such as twigs.     

Lateral Hyporheic Zone Chemistry in an Artificially Constructed Gravel Bar and a Re‐Meandered Stream Channel,Southern Ontario,Canada1

Abstract: The effect of stream restoration on hyporheic functions has been neglected, although channel rehabilitation projects have a potential to alter stream‐ground‐water interactions. The present study examined the effect of an artificially constructed gravel bar and re‐meandered stream channel on lateral hyporheic exchange flow and chemistry in two lowland N‐rich streams in southern Ontario, Canada. Nitrate concentrations were relatively high, ranging from 0.5 to 1.3 mg N/l in both streams during spring through fall months. However, nitrate concentrations showed a steep decline as stream water entered the gravel bar and the meander bends. Differences between observed and predicted nitrate concentrations based on conservative ion concentration patterns indicated that 40‐100 and 68‐98% of the nitrate entering the hyporheic zone was removed in the gravel bar and meanders, respectively. Rapid depletion of dissolved oxygen concentrations along lateral hyporheic flow paths and denitrifying potentials assayed by the acetylene block technique in hyporheic sediments suggests that denitrification was an important mechanism of nitrate depletion. Despite the high rate of nitrate removal, the flux of stream water laterally entering the constructed gravel bar and meander bends was very small, and hyporheic nitrate removal was <0.015% of the daily stream load during base‐flow periods in summer and fall. The effects of restoration projects on hyporheic zone dynamics are often limited in lowland streams by low channel gradients and fine floodplain sediments with low interstitial flows that restrict the magnitude of the stream‐hyporheic connection.     

Denitrification and availability of carbon and nitrogen in a well-drained pasture soil amended with particulate organic carbon

A well-drained soil in N-fertilized dairy pasture was amended with particulate organic carbon (POC), either sawdust or coarse woody mulch, and sampled every 4 wk for a year to test the hypothesis that the addition of POC would increase denitrification activity by increasing the number of microsites where denitrification occurred. Overall mean denitrifying enzyme activity (DEA), on a gravimetric basis, was 100% greater for the woody mulch treatment and 50% greater for the sawdust treatment compared with controls, indicating the denitrifying potential of the soil was enhanced. Despite differences in DEA, no difference in denitrification rate, as measured by the acetylene block technique, was detected among treatments, with an average annual N loss of ～22 kg N ha yr Soil water content overall was driving denitrification in this well-drained soil as regression of the natural log of volumetric soil water content (VWC) against denitrification rate was highly significant ( = 0.74, < 0.001). Addition of the amendments, however, had significant effects on the availability of both C and N. An additional 20 to 40 kg N ha was stored in POC-amended treatments as a result of increases in the microbial biomass. Basal respiration, as a measure of available C, was 400% greater than controls in the sawdust treatment and 250% greater than controls in the mulch. Net N mineralization, however, was significantly lower in the sawdust treatment, resulting in significantly lower nitrate N levels than in the control. We attribute the lack of measured response in denitrification rate to the high temporal variability in denitrification and suggest that diffusion of nitrate may ultimately have limited denitrification in the amended treatments. Our data indicate that manipulation of denitrification by addition of POC may be possible, particularly when nitrate levels are high, but quantifying differences in the rate of denitrification is difficult because of the temporal nature of the process (particularly the complex interaction of N availability and soil water content).     

Recirculating sand filters for treatment of synthetic dairy parlor washings

Land-spreading and spray irrigation are the most widely used practices for the disposal of dairy wastewaters in Ireland but in some cases there can be problems due to contamination of surface and ground water. The use of intermittent sand filtration has been suggested as an alternative treatment process. However, a single pass through a sand filter limits denitrification because of the absence of reducing conditions following nitrification and the lack of an available carbon source. This leads to poor total nitrogen (TN) reduction and an effluent that is high in nitrate nitrogen (NO3-N). This paper follows a previous paper in which two instrumented stratified sand filter columns (0.9 and 0.425 m deep, and both 0.3 m in diameter) were intermittently loaded with synthetic dairy parlor washings at a number of hydraulic loading rates, leading to a TN reduction of 27 to 41%. In the present study, under a chemical oxygen demand (COD) of 23.4 g m(-2) d(-1), the TN was reduced by 83.2% when three-quarters of the sand filter effluent was recirculated through an anoxic zone. This produced an effluent NO3-N concentration of 60 mg L(-1). With recirculation, the improvement in the removal of organic matter and ammonia N (NH4-N) is minimal. Recirculating sand filters appear to offer a mechanically simple and effective method for the removal of nitrogen from dairy parlor effluents and are a significant improvement over a single-pass sand filter.     

高浓度氨氮废水好氧反硝化反应的基本条件

文章通过室内实验,对高浓度氨氮废水(垃圾渗滤液)间歇曝气,在只存在有机碳、无机氮的条件下进行好氧反硝化脱氮研究。实验结果表明:垃圾渗滤液中存在好氧反硝化土著微生物菌落;发生好氧反硝化的基本条件为在溶解氧充足的条件下间歇曝气;碳源不仅是厌氧反硝化所必须的,同样也是好氧反硝化的必要条件。